The invention relates to an arrangement and a substrate, and also to a method for preparing a cell sample.
Cell analysis, more particularly single cell analysis, in which a cell sample comprising a multiplicity of individual cells is analyzed, is an essential basis for prognostic and therapeutic applications in clinical medicine. By way of example, the detection of disseminated tumor cells represents a great challenge to the equipment used for the analysis.
For the purpose of single cell analysis of large sample amounts, such as e.g. 10 ml whole blood, use is primarily made of fluorescence microscopy. An essential precondition for meaningful microscopy is a controlled and sparing sample preparation in which, inter alia, the cells to be examined by microscopy have to be brought into the same focal plane of the microscope. To this end, substantially two approaches, which moreover allow high flow, are known:                In the so-called fluorescence activated cell sorting (FACS) method, the individual cells are moved and are individually transported through a capillary. Fluorescence is detected there with the aid of fixed optics. The FACS method makes it possible to detect optical information in the form of stray light and fluorescence. However, disadvantageously, the sample preparation is carried out using erythrocyte lysis, which can typically lead to losses in the cells to be analyzed.        In an alternative method, the cells are fixed on a substrate and the microscope optics scan a comparatively large area, on which the cells are fixed. The single cells are present in the form of a cell suspension. Two methods are known for the preparation. In the method by Cytotrack, the cell suspension is poured onto a substrate that is similar to a CD. The individual cells are subsequently scanned in a fashion that, in principle, is equivalent to the read procedure of a CD. This takes about 30 minutes. The cell suspension can also be poured onto e.g. a large-area support such that the cells are to be scanned with the aid of a bundle of optical waveguides. By way of example, this should make it possible to scan 60 million cells in a 10 ml blood sample within approximately 80 minutes. A disadvantage of both these methods is that large substrates are required, onto which the cell suspension is poured. There likewise is a need for complicated scanner optics, possibly with a translation stage. Moreover, there must be a relatively complicated pre-enrichment of cells, during which cells are initially marked magnetically and the marked cells are subsequently selected by e.g. applying a magnetic field.        In a further approach, the sought after tumor cells are purified by e.g. an immunomagnetic method or by centrifugation techniques such as e.g. the so-called “OncoQuick” method by Greiner Bio-One and subsequently scanned using fluorescence microscopy, e.g. a system from Wavesense, instead of scanning the entire sample volume for individual cells like above. A disadvantage here is that a plurality of sample preparation steps are required, with some analytes being lost in each step.        US 2008/0206774 A1 has disclosed a method for preparing a blood cell sample.        